Condensed Matter Seminar: Universality of ultracold Bose gases at interaction extremes

Victor Colussi (Eindhoven University)
When processes at short distances are not Pauli suppressed, intrinsically multi-body physics can play an important role in a many-body system.

Victor Colussi (Eindhoven University)
Online Seminar
Mon 10. February 2020, 11:30 am (MEZ)

Abstract:

When processes at short distances are not Pauli suppressed, intrinsically multi-body physics can play an important role in a many-body system.  For ultracold Bose gases at infinite scattering length, two-body interactions are as strong as allowed by quantum mechanics, and properties of these unitary systems are expected to depend universally on density scales of the medium.  I discuss how this picture is altered due to Efimov physics [1], where an infinity of three-body bound trimers emerge, with the possibility forming condensed triplets.  In the opposite limit where two-body interactions are nearly switched off, effective three-body interactions determine the quantum phase diagram in the vicinity of a tricritical point separating gas and liquid phases from the vacuum [2].  I discuss how these interactions are universally determined by the long-range van der Waals interaction, which has consequences for observing liquid droplets stabilized by three-body mechanisms [3].

References

[1] Colussi, Corson, D’Incao, PRL 120, 100401 (2018)
[2] Zwerger, J. Stat. Mech. 2019, 103104 (2019)
[3] Mestrom, Colussi, Secker, Groenevld, Kokkelmans, arXiv:1912.10812